Development of a Pressure Related Assessment Model of Seating Discomfort

This study consisted of the development of a factor model and a sitting interface pressure related assessment model of sitting discomfort, based on an extensive literature review. The factor model identified the force applied on the sitter's body as one of the main factors causing seating discomfort. The assessment model proposed that sitting discomfort mainly arises from feelings in the lumbar and buttock areas, and that local discomfort either depends upon or, is reflected by, the interface pressure. A pilot experiment was conducted to explore the utility of the assessment model by change of postural angles. Eleven subjects attended a 40 min sitting session. The independent variables were seat angle and seat-to-backrest angle. A pressure measuring device was used to record interface pressure between the subject and a prototype seat surface. A general comfort scale was administered after each pressure measurement. Results showed that all pressure measures were sensitive to postural changes of varied angulation, and that subjective ratings of comfort correlated with pressure measures, especially maximum pressure, average pressure ratio and maximum pressure gradient. Evidence from the pilot suggested that the model may have utility and eventually be used to assess seating discomfort.